The present disclosure relates generally to photolithography, such as is used in the manufacture of semiconductor integrated circuits.
Photolithography is a mechanism by which a pattern on a mask is projected onto a substrate such as a semiconductor wafer. In areas such as semiconductor photolithography, it has become necessary to create images on the semiconductor wafer that incorporate minimum feature sizes under a resolution limit. The mask pattern needs to be optimized for producing the image with as little distortion as possible.
Often, diffraction from a mask and a lithography system causes imaging distortion and degradation. For example, a square corner on the mask may be imaged as a round corner on the semiconductor wafer. To address this problem, many semiconductor photolithography systems use optical proximity correction (OPC) techniques and software in an attempt to optimize the existing mask pattern on a segment-by-segment, edge-by-edge, and/or polygon-by-polygon manner. However, the pattern layout optimization and correction by OPC software lacks optimization freedom and may be easily trapped into a local minimum prior to full optimization. Furthermnore, the OPC software is pattern specific.